Fluorescence microscopy is required for the research in the newly funded grant R35GM118175. This application is to allow the purchase a fluorescence microscope. The need for fluorescence microscopy is clear from our previous research funded by two R01 applications folded in the R35 award mechanism. More than half of the project description for R35GM118175 involves the analysis of mouse and cell mutants for proficiency in recombination: meiotic recombination, mitotic recombination (somatic cells), and replication fork protection, and live cell imaging will add a new dynamic.